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WILLIAM AL'LENDER, OF NEW LONI0N, CONNECTICUT.

Letters Pate-nt No. 75,106, dated Zifarck 3, 1868.

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TO ALL- WHOM IT MAY CONCERN:

Be it known that I, WILLIAM ALLnNDnR,of New London, in the county of NewLondon, and State ot Connecticut, have invented certain new and usefulImprovements in Casting Aluminum Plates on to Artificial Teeth, anduniting 'the two firmly without risk of fracture from the exceedinglycontractile nature of that metal; and that the following is a full,clear, and exact description ot the same, reference being had to theaccompanying drawing, making a. part of this specification, in which- -IFigure 1 represents in perspective a set of teeth on or in an aluminumplate, made after my general plan.

Aluminum possesses, in a high degree, many essential propertiesrequiredin dentistry, and especially in plates for holding artificialtecth,as follows: It is light, very stiii', anti-corrosive, is renderedluid at a low temperature, and susceptible of a. high finish. But, owingto its very great contraction in cooling, it has heretofore beeny foundimpossible, except by accident, to cast it upon other substances withoutfracturing itseif, or the substance on which it is cast, by itscontractile force.

After much experiment in the use of'aluminum for plates for holdingartificial teeth, I have discovered a mode of casting this metal uponteeth which entirely avoids the risk of fracture, and enables me tointroduce its use in dentistry withl great advantage and economy. V i

My invention consists in providing means for compensating or talringupthe extraordinary contraction of aluminum in casting it upon teeth, soas to avoid fracture of the metal or of the teeth, and thus utilizing indentistry a metal havingmany valuable qualities for that art, but whichhas heretofore, in practice, been found impracticable on account of itsimmense contraction in cooling, and which exceeds that of any othermetal available in dentistry. v

An indispensable element` in the economy of dentistry is to form or castthe mouth-plate upon the teeth, so that the act of casting shall firmlyunite the teeth to said plate. This makes a firm, substantial union, notattainable by other separate appliances without very great labor andexpense. And my invention embraces this plan of casting, but inconnection with a metal (aluminum) which from its very nature opposessuch process, as above mentioned, from the diiculty in arresting orcompensating for its immense contraction in cooling.

To enable others 'skilled in the art to make and uso my invention, Iwill proceed to describe the same with reference to the drawing. i

Having articulated or antagonized the teeth, I separate the blocks ofteeth, a ct a, so that the contrae-` tion of the aluminum, when castupon them, will not, in cooling, break them The space left betweenl theblocks of teeth, when moulded, is covered by a strip of aluminum, orother metal or material, to prevent the encroachment or introduction ofthe molten metal, or any other substance used in moulding or casting,from entering said space which would prevent the blocks from comingtogether closely, and 'making a neat union. Iheprevcntionof anysubstance getting into the space between-thc blocks I prefer, but a.substance may be introduced into this space, which will yield and allowthe blocks to come up close together, or which may be forced intocavities in the adjacent edges of such blocks when forced together,l theobject being to prevent any such substance getting into the space asmight in any manner prevent the blocks from coming close up, and thusclosing said space.

To prevent the contractile force of the aluminum from acting on thcblocks individually, the portion ofthe teeth covered by the metal' mustbe so made or ground as to prevent the metal from grasping them, thatis, there should bc no indented or ovcrhanging points or surfaces, butplain and tapering, or wodgc-shnped, so that the metal may draw or slipover such surfaces in contracting, wit-hout seizing upon them, whichlatter invariably results in fracture. And as the contractile force istowards the centre of the block, the pins or rivets inthe teeth orblocks should .all point towards the centre of the block, the centre onestraight, and the others 'acutely bent towards it, which allows thcmetal to slip from the pins or rivets in the line in which itscontraction tendsA Itis better to so arrange the pins or rivets as thatthey will point towards thc centrc'oi` the block, or towards the line ofgreatest contraction, but the contractile force may be used to bend orpoint them in that direction, by putt-ing around them, in whole or inpart, previous to the pouring of the molten metal into the mould,aluminum in wire,t`oi1, sheet, or otherwise shaped, or plaster of Paris,or other substance, near where they enter the blocks, to allow them tobend, when the contractile force comes upon them, and take the directionot' that force.

Blocks of teeth may be made with a groove running parallel with or inthe general direction ot' the cuttingedges or outer faces of the teeth,and the blocks may be set in a mould, together or slightlyiseparatcd,andthe molten aluminum poured into this groove, und its contractionbeing in the line of the groove, it-wouhl thus be prevented fromobtaining a hold on the blocks and breaking them.

The moulds I prefer to use are so madens to allow the flow or casting ofthe metal around und beyond the Vouter face'o` the teeth, to counteractthe effect ot' the contraction oi the central portion of the plate, orthat part which is within the circle described-by the inner face of theteeth. The moulding of the teeth preparatory to the pouring of thealuminum around them does not diii'er, otherwise than heretoforementioned, from the moulding of teeth for other cast substances, exceptsuch additional preparations as the use of this peculiar metal(aluminum) demand. l

The contraction et' the metal may be regulated also by means of currentsof ai-r or water carried into the moulds or any part thereof` which itismost desirable to so operate upon, and may be. done by layingwax inthe mould, which, `when melted out, will leave a channel or space,through which it may be carried or forced; and

i the strain, or a portion of the strain, of the contractile forceo` thealuminum, maybe taken from the teeth by laying in proximity to or incontact with the teeth, pieces or strips of metal, which strips shalloppose the force of the contracting metal. The teeth may bef-asten ed tothese strips, which may be twisted or worked together, or, if singlestrips, screw-cut or otherwise.

As, from the very light specific character of this metal, (aluminum) andthe low temperature yrequired to put it in a Huid or molten condition,its natural flow is very sluggish, I may or can use a type-founderspump, or forcing-apparatus, to force the metal into and through themoulds.

The mould or form of teeth, when ready to receivethe molten aluminum,may be heated, as is usual in other processes of casting. l

Having thus fully described my invention, what I claim therein as new,and desire to secure by Letters Patentis- 1. In combination with thepouring of molten aluminum to form a base for artificial teeth, the somaking or grinding ofi` the blocks of teeth,'desi'gned for the receptionof molten aluminum as a base, as that the metal cannot seize or gripe,but slip upon, Vthe teeth or blocks, in contracting, and thus preventthe fracture of the metah: or of the teeth, or blocks of teeth,substantially as described.

2. I also claim, in combination 1with teeth or blocks of teeth, on whichaluminum is to be cast for a base, the pointing of the pins or rivetstowards cach other, or towards the centre of the block, or in the lineof the greatest contraction, substantially as described.

3. Iaiso claim, in combination with 4the moulding of teeth or blocks ofteeth, or preparing them to receive molten aluminum, which is to formtheir base, the protected space between them, to guard against theentrance ofthe metal or other material, as described, so that thecontractile force of the aluminum, in cooling, may draw them uptogether, or nearly so, substantially as` described.

WILLIAM ALLENDER.

Witnesses:

A. B. S'roncufron, EDM. F. BROWN.

